In recent years, electronic equipment such as a mobile telephone, a PDA or a personal computer has become widely used as a communication unit and an information processing unit. However, with that, examples of theft or loss due to leaving etc. often occur and the risk of a leak of personal information such as a telephone book or unauthorized use by other people increases. Therefore, a technique for improving security becomes increasingly important.
An example of a use limiting apparatus of equipment constructed so as to include a mobile telephone 1 and a key 10 attached to these pieces of equipment and capable of being always carried by a user of the equipment and identification codes are mutually communicated (hereinafter called polling) and thereby, use limiting of the pieces of equipment 1 to 3 is released and when a mutual distance is separated at a predetermined distance or longer and a reception level reduces, release of the use limiting of the pieces of equipment 1 to 3 is stopped and the pieces of equipment are disabled and also an alarm signal is issued by a wireless communication unit (hereinafter called a key) 10 has been known conventionally (for example, see Patent Reference 1).
Patent Reference 1: JP-B-2931276